Biotin intermediate



- Patented May 14, 1946 v Wilbur. I. Patterson, Fairfax, Va., and-Joseph V. Karabinos, Columbus, Ohio, asslgnors, by mesne I assignments, to Wyeth Incorporated, Philadelphia, Pa., a corporation)! Delaware No Drawing. Application June so, 1943,

I Serial No. 492,977

a z Claims. or. 260-329) F This invention relates to the synthesis of a compound with the ring structure of biotin (vitamin H) and more particularly to an intermediate or such synthesis.

Several methods of approach to of biotin have been used and inthe present case the intermediate disclosed herein has been isothe 'sydthesis formed colorless crystals from ethyl alcohol;.

M. P. 162-163. I

Meso-,2,3-diethoxy-1,4-diidobutane.-A solution of 25 g. (0.15 mole) of potassium iodide in lated as a step of the synthesis approach through dihydroxytetrahydrothiophene. In its broadest sense the invention consists in reacting a butane compound containing mercury with iodine in the presence of carbon tetrachloride and thereafter forming 3,4-dihydroxytetrahydrothiophene. this latter compound being an intermediate in the synthesis of biotln Y I As an illustrativeexample. of the preparation of this intermediate the following is given:

Mesa-1,4-diacetoxy mercuriZJ-diethoxy butane.Forty grams 0.1 5 mole) ofmercuric acetate and 225 cc. of abs lute ethyl alcohol were .placed in a 500 cc. filtering fiaskrltted with a large expansion bulb reachingnearlyto the bottom of the flask. Gaseous butadiene (0.06'7 mole) from the sulfone, or from a measured quantity of liquid butadlene in a test-tube, was introduced 50 cc. of water was added with stirring to'a suspension of 50 g. (0.075 mole) of the meso diacetxy-mercury compound (M. P. 162-163") in 200 cc. of water.

After stirring for thirty minutes. the precipitate of 2,3-diethoxy-1,4-diiodomercuributane was filtered with suction and allowed to dry in the air. The yield was practically quantitative.

The diiodomercury compound was refluxed with 200 CC.',Of carbon tetrachloride and 39 g. (0.153

mole) of iodine for two hours. Mercuric iodide appeared after the first few minutes of heating;

, the mixture was still colored due to excess iodine through the side tube of the filtering flask. The

reaction mixture wasshakento facilitate absorption of the gas. After the absorption started the flask was placed on a hot-plateand maintained just below the boiling point of the alcohol. The mercuration canbe carried out with good results at room temperature but a longer time is required since the mercuric acetate dissolves quite slowly. When all of the butadiene had been absorbed at, ptest portion of the solution was withdrawn and made alkaline with aqueous sodium hydroxide.

I If a yellow precipitate of mercuric oxide formed,

a small additional quantity of butadi'ene was introduced and the absorption process continued until the sodium hydroxidetest was negative.

The mercuration mixturewas allowed to cool to 20 and the crystals of the less soluble product (alpha-isomer) were filtered with suction and The first crop of crys- T tals weighed 20-2 3 g. The filtrate and washings washed twice with ether.

were subjected to distillation on a steam-bath until most of the alcohol had been removed. The residue was filtered when cold and the filtrate was reserved for isolation of the more soluble product (beta-isomer). crystals of the beta-isomer was washed with ether and combined with the first crop, giving a 1 total of about g. (%yield, based on mercuric acetate) of the alpha-isomer. The product yield). After three crystallizations from' at the end ofthe-heating period. The reaction mixture'was filtered while hot and the residual mercuric iodide was w'ashed'with three portions of hot carbon tetrachloride. The filtrate and washings were evaporated until the solvent had "been removed completely and then treated with hot water containing sodium bisulfite until the iodine color had disappeared. The product liquefied under hot water but crystallized on cooling. The crude material weighed 25-26 g.

ethyl alcohol, and drying over calcium chloride,- the product formed colorless crystals, M. P. 52-53".

3,4-diethoxytetrahydrothiopmane-Forty-eight" and one-half grams of l,4-diiodo=2,3-diethoxybutane (V) (prepared\by the method of John R.

Johnson, William H. Jobling, GeorgeW. Bodamer JACS: 63: 131:1.941) was refluxed with 250 cc. of

-. 80% ethanol containing 50 grams of potassium sulfide. The alcohol was removed by distillation and after the addition 01' cc. of water-the residue. was steam distilled.

(500 cc.) was extracted twice with ethyl acetate (400 cc. total) and the solvent evaporated in vacuo. The residue was distilled in vacuo using an aspirator and 12 g. "of product boiling at -117? was obtained. The yellow liquid had an odor resembling kerosene. p

AnahCalcd. fO'r CaHwOzS: C, 54.50: H, 9.15

Found: C, 53.6; 'H, 8.8. I

, 50 The second crop of The above liquid when treated withan aqueous solution of mercuric chloride gave a precipitate which was recrystallized several times from dilute alcohol and then melted at 142-4".

3,4 d i h g d r o a: ytetrahydrothiophene.--Two grams of the diethoxytetrahydrothiophene were refluxed for 2 hours with 20 cc. of constant boil- The distillate ing hydrobromic acid. The mixture was then concentrated in vacuo to a heavy sweet smelling The reaction is indicated by the following The crude product weighed What we claim is:

1. 3,4-dihydroxytetrahydrothiophene.

2. The process of preparing 3,4-dihydroxytetrahydrothiophene which consists in preparing meso-lA-diacetoxy mercuri 2,3-diethoigvbutane,

reacting said compound with an aqueous solution of potassium iodide to form 2,3-diethoxy-1A-diiodomercuributane, reacting said diiodomercuributane compound with iodine to produce 2,3-di- ,ethoxy-lA-diiodobutane, reacting said diiodobu- 'tane compound with potassium sulfide to form 3,4 diethoxytetrahydrothiophene and reacting said thiophene compound with hydrobromic acid to form 3,4-dihydroxytetrahydrothiophene.

f WILBUR I. PATTERSON. JOSEPH V. KARABINOS. 

